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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Method and device for a high temperature vacuum-safe solder resist utilizing laser ablation of solderable surfaces for an electronic module assembly

A process for manufacturing an electronic component having attaches includes providing a first component having a first attach, forming trenches on a portion of the first attach with a laser to form a solder stop, and providing a second component comprising a second attach. The process further includes providing solder between the first attach and the second attach to form a connection between the first component and the second component, where the trenches contain the solder to a usable area. A device produced by the process is disclosed as well.

Stabach, Jennifer↗
DOE OSTI2026

Machine Learning for Mapping Multipactor Susceptibility in RF Systems: Capabilities and Generalization Constraints

Multipactor is a surface-driven electron avalanche phenomenon that degrades the performance and reliability of radio-frequency (RF) systems in particle accelerator and vacuum electronics applications. Multipactor behavior in a given device structure is conventionally assessed through susceptibility charts, which provide a parameter-space characterization of the instability. In this work, we assess the capabilities of machine-learning (ML) models to learn and predict such susceptibility charts and analyze the constraints governing their generalization across materials. Using a simulation-derived dataset spanning six distinct secondary-electron-yield material profiles in a canonical two-surface planar geometry, we train supervised regression models and artificial neural networks to predict the time-averaged electron growth rate, δavg, across the relevant parameter space. Model performance is evaluated using metrics that explicitly probe the structure of susceptibility charts, including Intersection over Union, Structural Similarity Index, and correlation analysis. Tree-based ensemble models outperform neural-network models in reconstructing susceptibility regions and in generalizing across material domains. Principal-component analysis reveals disjoint material feature distributions, indicating that the piecewise mode structure of multipactor susceptibility is difficult to represent with a single global model and that generalization is constrained by data coverage rather than by model complexity. An exhaustive reduced-coverage study further shows that sparse material-space coverage can yield mean performance in the same general range but producing large variability in the susceptibility-region overlap. These results clarify the capabilities of ML-based surrogate models for parameter-space characterization of multipactor discharge. They also provide guidance for their appropriate use in RF system design.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Direct intercalation of MoS 2 and WS 2 thin films by vacuum filtration

In the development of next-generation electronics and energy devices, intercalation compounds of transition metal dichalcogenides (TMDCs) are gaining attention for their unique properties that result from synergistic interactions between guest species and host materials. Nowadays, intercalation compounds of MoS 2 and WS 2 are commonly prepared by a two-step process: (1) exfoliation to form single-layer and/or few-layer nanosheets and (2) restacking the nanosheets with the guest species by vigorously mixing the exfoliated suspension with the solution of guest species. While a wide variety of intercalation compounds have been synthesized using this approach, the intercalation process is often timeconsuming, and the product slurry limits material quality and impedes characterization and applications. Herein, we report a versatile method for preparing intercalated TMDCs in a thin-film morphology. Using this approach, we successfully prepared a range of existing intercalation compounds of MoS 2 and WS 2 (e.g., ferrocene and amine intercalated MoS 2 and WS 2 ). Additionally, by leveraging the versatility of this intercalation method, we report we intercalated phenazine and benzoquinone into MoS 2 and WS 2 for the first time.

36 MATERIALS SCIENCE↗
DOE OSTI2020

All-vacuum-deposited inorganic cesium lead halide perovskite light-emitting diodes

Polycrystalline CsPbBr 3 thin films are deposited by vacuum co-evaporation of cesium halide and lead halide precursors, leading to uniform pinhole-free morphology and precise control over the film thickness and precursor stoichiometry. By utilizing the organic hole and electron transport layers, all-vacuum-deposited perovskite LEDs are fabricated. The resulting devices exhibit a maximum luminance of 1800 cd/m 2 , a 531 nm emission wavelength peak with a spectral linewidth of 21 nm, and an external quantum efficiency of 1.1%.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Open-Air Manufacturing of Efficient Large-Area Perovskite Solar Cells to Meet Stability and Cost Targets

This SETO-funded project (DE-EE0009516) developed a fully open-air manufacturing pathway for perovskite solar cells and modules, eliminating vacuum-based processing steps while improving device stability. Open-air ultrasonic spray deposition, solution combustion synthesis, rapid thermal processing, and atmospheric plasma curing were developed and optimized for all functional device layers — perovskite absorber, hole transport layers (HTLs), electron transport layers (ETLs), transparent conducting oxides (TCOs), and rear electrodes — without reliance on vacuum. Sprayed organic ETLs preserved perovskite crystal structure and enabled power conversion efficiencies exceeding 20%, and open-air processed TCOs and rear electrodes achieved optoelectronic performance comparable to sputtered alternatives at substantially lower manufacturing cost. Device stability was assessed through accelerated aging protocols aligned with IEC and ISOS standards, combined with high-throughput optical diagnostics that identified key degradation mechanisms and antagonistic interactions among heat, humidity, and illumination stressors. A comprehensive technoeconomic analysis quantified the cost and throughput advantages of open-air manufacturing over conventional vacuum-based processes, identifying vacuum deposition as the dominant cost driver and demonstrating a clear pathway toward the $0.02/kWh target. The project produced five peer-reviewed journal publications, eleven conference presentations, two patents/applications, and five Ph.D. dissertations.

14 SOLAR ENERGY↗
DOE OSTI2021

Ultraviolet (UV) light emitting device (LED) driven photocathode

An apparatus includes an electromechanical x-ray generator (MEXRAY) configured to charged capacitors using a small, high-voltage direct current. The apparatus also includes an ultraviolet (UV) light emitting diode (LED) driven photocathode device configured to control/modulate an electron dose rate of the MEXRAY or other vacuum DC, source.

Watson, Scott Avery↗
DOE OSTI2021

Ultrafast Charge Transfer Dynamics at the Origin of Photoconductivity in Doped Organic Solids

In spite of their growing importance for optoelectronic devices, the fundamental properties and photophysics of molecularly doped organic solids remain poorly understood. Such doping typically leads to a small fraction of free conductive charges, with most electronic carriers remaining Coulombically bound to the ionized dopant. Recently, we have reported photocurrent for devices containing vacuum-deposited TAPC (1,1-bis(4-bis(4- methylphenyl)aminophenyl)cyclohexane) doped with MoO 3 , showing that photoexcitation of charged TAPC molecules increases the concentration of free holes that contribute to conduction. Here, we elucidate the excited-state dynamics of such doped TAPC films to unravel the key mechanisms responsible for this effect. We demonstrate that excitation of different electronic transitions in charged and neutral TAPC molecules allows bound holes to overcome the Coulombic attraction to their MoO 3 counterions, resulting in an enhanced yield of long-lived free carriers. This is caused by ultrafast back-and-forth shuffling of charges and excitation energy between adjacent cations and neutral molecules, competing with relatively slow nonradiative decay from higher excited states of TAPC •+ . The light-induced generation of conductive carriers requires the coexistence of cationic and neutral TAPC, a favorable energy level alignment, and intermolecular interactions in the solid state.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Improved Fundamental Understanding of Aluminum Chemistry and Interactions of Aluminate Anion with Co-Anions: ORNL Project Progress Report

The U.S. Department of Energy (DOE)’s Hanford Site in Washington State houses 177 underground storage tanks containing millions of gallons of nuclear and chemical waste with high aluminum content. Aluminum (Al) salt reactions with strong bases produce aluminum hydroxides, like boehmite (γ-AlOOH), which are main components of insoluble nuclear waste sludge. Understanding the morphology, crystallinity, and dissolution behavior of boehmite under waste tank conditions is necessary for improving waste management and mitigation strategies. The ORNL team uses in situ multimodal analysis strategy to study Al chemistry of simulated tank waste using microfluidic reactors and advanced chemical imaging and mass spectrometry (MS) techniques. Because the SALVI device is vacuum compatible and transferrable among different platforms, we can use it in scanning electron microscopy (SEM), vacuum ultraviolet single photon mass spectrometry (VUV SPI-MS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to study the chemical speciation and colloid stability in liquids in this project. Additionally, ex situ transmission electron microscopy (TEM) and x-ray diffraction (XRD) spectroscopy can be used to verify particle phase to further the understanding of the Al-bearing phases. This report gives a summary of the technical progress of the ORNL tasks. A plan for year 2 performance is recommended in the summary.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

A multi-chord, two-color interferometer using Hilbert transform phase detection for measuring electron density in spheromak plasmas

A new, four-chord, CO 2 /He–Ne heterodyne interferometer has been designed and built for measuring line-averaged plasma density in the HIT-SI3 and subsequent HIT-SIU sustained spheromak devices. The two-color system successfully eliminates vibration-induced errors caused by mirrors that are secured to the vacuum chamber and is able to resolve electron densities ne in the full operating range of 10 18 –10 20 m –3 in both experiments with an integrated error of 4.7 × 10 17 m –2 . Here, data are presented from high toroidal current plasma discharges, showing the time evolution of electron densities n e and j Φ /n e along multiple chords.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Material Plasma Exposure eXperiment (MPEX) High Heat Flux Bellows for Component Alignment in High Microwave Environment

The Material Plasma Exposure eXperiment (MPEX) device is a linear plasma device developed to perform plasma material interaction experiments under the conditions prototypic of a fusion reactor divertor. MPEX has multiple systems that must be precisely aligned to the plasma axis, including an electron cyclotron heating system that emits up to 400 kW of microwave power into the vacuum vessel. Five distinct systems require precise alignment on the MPEX device, thus requiring four bellows, all of which are adjacent to the plasma at a relatively high heat flux of approximately 47 kW/m2 and microwave power regions. The MPEX high heat flux bellows (HHFB) is designed to deliver 6 degrees of freedom positioning. The HHFB includes titanium–zirconium–molybdenum (TZM) inserts that are brazed into a Glidcop AL-15 body using a high-temperature braze alloy, thus blocking direct line of sight to an edge-welded bellows from the plasma and microwave screen to block microwaves from the bellows. Further, a custom ConFlat knife edge is machined into the Glidcop AL-15, so the vacuum flanges do not need a braze or weld joint on the vacuum interface. Fingerstock or copper mesh is used to restrict microwave power from entering the interstitial space between the water-cooled Glidcop AL-15 body and edge-welded bellows. Glidcop AL-15 was selected as the material of choice for the water-cooled body because it can maintain mechanical integrity at elevated temperatures, and it also allows for a high-temperature braze. TZM was selected for its machinability and compatibility with vacuum and plasma requirements. A test article is also being considered for a similarly shaped component, the MPEX limiter, that will demonstrate the integrity of the braze joint under high thermal load. Results from this testing will be extrapolated to deduce the lifetime and integrity of the HHFB design.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Frontiers in the Application of RF Vacuum Electronics

The application of radio frequency (RF) vacuum electronics for the betterment of the human condition began soon after the invention of the first vacuum tubes in the 1920s and has not stopped since. Today, microwave vacuum devices are powering important applications in health treatment, material and biological science, wireless communication-terrestrial and space, Earth environment remote sensing, and the promise of safe, reliable, and inexhaustible energy. This article highlights some of the exciting application frontiers of vacuum electronics.

42 ENGINEERING↗
DOE OSTI2022

Collisional Effects on Electron Trajectories in Crossed-Field Devices

Crossed-field diodes (CFDs) are used in multiple high-power applications and are characterized by an applied magnetic field orthogonal to the electric field, induced by the applied voltage across the anode-cathode gap. In vacuum, the Hull cutoff magnetic field (HCMF) represents the maximum applied magnetic field for which an electron from the cathode can reach the anode. This study investigates the effects of non-vacuum conditions on electron trajectories by introducing electron mobility, which represents particle collisions. We used numerical solutions of the electron force law and particle-in-cell simulations (XPDP1) to assess electron motion for various electron mobilities. For magnetic fields above the HCMF in vacuum, reducing the electron mobility increases the time for an electron emitted from the cathode to reach the anode. Reducing mobility below 22 C s/kg eliminates the HCMF for any magnetic field, meaning that an emitted electron will always cross the gap. We derived the magnetic field, mobility, and electron transit time corresponding to this condition by solving for the condition when the electron velocity in the direction across the anode-cathode gap going to zero at the anode. A parametric study of these conditions using theory and XPDP1 is performed under different gap distances, voltages, and magnetic fields.

42 ENGINEERING↗
DOE OSTI2021

Bottom‐Up Synthesized Nanoporous Graphene Transistors

Abstract Nanoporous graphene (NPG) can exhibit a uniform electronic band gap and rationally‐engineered emergent electronic properties, promising for electronic devices such as field‐effect transistors (FETs), when synthesized with atomic precision. Bottom‐up, on‐surface synthetic approaches developed for graphene nanoribbons (GNRs) now provide the necessary atomic precision in NPG formation to access these desirable properties. However, the potential of bottom‐up synthesized NPG for electronic devices has remained largely unexplored to date. Here, FETs based on bottom‐up synthesized chevron‐type NPG (C‐NPG), consisting of ordered arrays of nanopores defined by laterally connected chevron GNRs, are demonstrated. C‐NPG FETs show excellent switching performance with on–off ratios exceeding 10 4 , which are tightly linked to the structural quality of C‐NPG. The devices operate as p‐type transistors in the air, while n‐type transport is observed when measured under vacuum, which is associated with reversible adsorption of gases or moisture. Theoretical analysis of charge transport in C‐NPG is also performed through electronic structure and transport calculations, which reveal strong conductance anisotropy effects in C‐NPG. The present study provides important insights into the design of high‐performance graphene‐based electronic devices where ballistic conductance and conduction anisotropy are achieved, which could be used in logic applications, and ultra‐sensitive sensors for chemical or biological detection.

Mutlu, Zafer↗
DOE OSTI2022

Flexible Copper Metal Circuits via Desktop Laser Printed Masks

A novel process is demonstrated that produces patterns of electrically conductive copper on a flexible polyimide film substrate using standard desktop laser printed toner and near room temperature aqueous chemistry. The laser toner acts as a mask to selectively block the ion exchange self-metallization (IESM) reduction reaction that forms nanoscale silver or palladium coatings at the polyimide surface. The silver or palladium IESM coating is then used as a catalyst for electroless deposition of copper. Under appropriate conditions, the copper is deposited selectively on top of the catalyst layer. The resulting copper layer has a measured sheet resistance as low as 0.3 Ohms/sq. Electrical isolation was measured between copper traces spaced as close as 300 microns, and high conductivity was measured along traces with widths as low as 200 microns. The minimum pattern size appears to be limited primarily by the resolution of the laser toner pattern, as the IESM metal layer was observed to follow the contours of individual toner particles. Here, the process avoids the use of high temperature, vacuum, and organic solvents and is thus suitable for very low cost prototyping or distributed manufacturing of simple electronic devices.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Impact of metal diffusion, lattice distortions, native defects, and ambient on dielectric breakdown in Ni–Ga 2 O 3 Schottky diodes

Ga 2 O 3 unipolar devices are of high interest due to their ~8 MV/cm predicted breakdown fields, which have not yet been achieved due to premature device failure. Pre- and post-failure defect analysis of Ni–Ga 2 O 3 Schottky diodes in ultrahigh vacuum (UHV) and air were performed using depth-resolved cathodoluminescence, high angle annular dark field scanning transmission electron microscopy, and energy dispersive x-ray analysis to understand the physical mechanisms that precede premature breakdown. The breakdown voltage in UHV was dramatically reduced by nearly 40% compared with the breakdown in air. This reduction in the breakdown voltage correlated with post-breakdown differences in Ni distribution, indicating that the coordination and bonding of Ni contribute strongly to electrical behavior in Ni–Ga 2 O 3 Schottky diodes. Breakdown studies in UHV revealed that Ni diffuses away more from the metal–semiconductor interface than with air breakdown, where Ni localizes more near the interface, indicative of the preferential formation of a Ni oxide under O-poor conditions. These measurements also identified the formation of divacancy-interstitial complexes and their characteristic luminescence signature ~150 nm from the interface, the densities of which correlated with breakdown fields. These findings show that electric-field-induced degradation occurs via the rearrangement of native point defects, which act as an additional precursor to device failure. Macroscopically, they show the impact of both vacuum conditions and metal reactivity on Ga 2 O 3 device fabrication.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Development of advanced vacuum technologies for extending plasma pulse duration on EAST

Advanced vacuum technologies, including pumping, fueling and wall conditioning, have been successfully developed or upgraded to efficiently control the fuel and impurity particles to extend the plasma pulse duration in the experimental advanced superconducting tokamak (EAST). To improve the particle exhaust rate cryopumps with a 60% increase in pumping speed and ∼2 times increase in saturation capacity have been developed, and molecular pumps with a ∼30% increase in pumping speed have been upgraded. In order to monitor the molecular pump status while avoiding bearing faults and overload accidents, a fault detection system has been built which can offer an early warning to avoid more losses within the fusion device. A series of fueling technologies have been developed including gas injection system, supersonic molecular beam injector, pellet injector (PI), massive gas injector and shattered pellet injector, installed at the midplane and divertor positions at different ports to improve fueling uniformity and efficiency. Meanwhile, routine wall conditioning such as electric and hot N 2 baking, ion cyclotron wall conditioning and glow discharge cleaning have been successfully developed to remove the impurity particles from the inner component and materials. The low Z material wall coating and real-time powder injection during plasma discharge are also designed and applied to further improve particle control capability. Finally, by using these advanced vacuum related technologies, good vacuum (<2 × 10 −6 Pa) and wall conditions are realized, and the fuel and impurity particles can be effectively and stably controlled, which promotes the achievement of the record plasma of ∼1056 s pulse duration with the line-averaged electron density of 1.8 × 10 19 m −3 on EAST. They provide a very important reference for vacuum system design and operation for future fusion devices.

EAST↗
DOE OSTI2023

Development of the high energy engineering X-ray (HEX) superconducting wiggler, magnetic measurement, installation, and commissioning

The High energy Engineering X-ray (HEX) diffraction beamline at the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Lab (BNL) is the first high-energy beamline capable of reaching 200 keV for a monochromatic beam. With the 3 GeV electron beam energy for the NSLS-II ring, only the superconducting wiggler (SCW) producing greater than 4 T peak field can cover these ranges with a sufficient number of photons. The 1.2 m-long HEX-SCW has a period length of 70 mm and a field strength on-axis of 4.3 T. It utilizes no liquid helium, and the vertical aperture size of the electron beam vacuum chamber is 8 mm. Unlike regular undulators/wigglers, there is no standard configuration for the magnetic measurement system for superconducting insertion devices. The NSLS-II Insertion Devices group has developed, in collaboration with the vacuum group, a novel in-vacuum Hall mapper with a 1.75 m in-vacuum linear motor and an in-vacuum flip coil system utilizing many commercial-off-the-shelf products. The measurements were conducted at the BNL, and the device was installed in the ring and commissioned. Here, this paper provides a description of the SCW and its magnetic measurement systems, as well as a brief account of the installation and commissioning efforts.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Wien filter with integrated vacuum pump

An integral Wien filter and vacuum pump for separating charged particles or for orienting their spin direction while maintaining optimal beamline vacuum. The vacuum pump is an ion pump including one or more cylindrical Penning cells to trap and expel electrons. The Wien filter includes orthogonal electric and magnetic fields to direct particles with the desired speed through the device while deflecting particles at undesired speeds. The Wien filter includes two electrodes, one biased positive and one biased negative, a dipole magnet, and means for reversing polarity of the electrodes to flip the spin of the charged particles. Metal plates on either side of the Penning cells embed gas that is ionized by trapped electrons in the Penning cell thus creating vacuum by turning gas into solid. The two metal plates can be configured to obtain vacuum pumping via chemical gettering and for removal of noble gases.

Poelker, Bernard Matthew↗